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b=DrC5gWSUJMcUvoYLDXbfHIwK1tb2VBfHwJxQHwh7TzSL5xh8sdvcpQx06xLCpGTzD 6QQbbuzI+A/83Qlo+5BQGNuXpAkQyO09qgmnhxbREexwqrM9/pbeWYilD3XQafjfXD HLxEIloCvEhH93/Qn0m2ZleVlXUNdrWWQldZwdOuIPMn2PXL+rj2ACGEwkcb3AhzfC 8VL8fzNYLHsdvEe95oaGzi6RelBNNgGhKSWy70B1SDCA6SFjt2zL0ax7ezldRCYICq v5gj8faxK3Pe1LhmNADlsWAcETHsfwvDKTaSu7gFesptWU5Y/ZMOVqtl5nwTqZCsqJ P7/gghhtBrsOw== Date: Wed, 29 Oct 2025 10:36:39 -1000 From: Tejun Heo To: Roman Gushchin Cc: Andrew Morton , linux-kernel@vger.kernel.org, Alexei Starovoitov , Suren Baghdasaryan , Michal Hocko , Shakeel Butt , Johannes Weiner , Andrii Nakryiko , JP Kobryn , linux-mm@kvack.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Kumar Kartikeya Dwivedi Subject: Re: [PATCH v2 02/23] bpf: initial support for attaching struct ops to cgroups Message-ID: References: <20251027231727.472628-1-roman.gushchin@linux.dev> <20251027231727.472628-3-roman.gushchin@linux.dev> <87ldkte9pr.fsf@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ldkte9pr.fsf@linux.dev> X-Rspam-User: X-Rspamd-Queue-Id: 8670F10000C X-Rspamd-Server: rspam02 X-Stat-Signature: i7dxozjnf9pzrgwihd6mnrqdegunbnhi X-HE-Tag: 1761770202-82583 X-HE-Meta: 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 ueLPO4pP DW80YSrxB74jT5peKqsJC1DZDocWcvXh3bnUduVL9GOWxtyCl1L3iD1nKko6yIdJ/MOyGWyto+hafqozTFGuiyhow8FrJlowDgwx1r0VAWqb8kj8jFiYMS9msqiejpnSi6d+dmqcxTWm0euYeCozJAUsVYSfG3T+GL1T8Q1dXt7j8cz4Rkcy+CrhKCFfUCagdX3eN1sEe/LA3W83h/CYABAAgsA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Oct 29, 2025 at 01:25:52PM -0700, Roman Gushchin wrote: > > BTW, for sched_ext sub-sched support, I'm just adding cgroup_id to > > struct_ops, which seems to work fine. It'd be nice to align on the same > > approach. What are the benefits of doing this through fd? > > Then you can attach a single struct ops to multiple cgroups (or Idk > sockets or processes or some other objects in the future). > And IMO it's just a more generic solution. I'm not very convinced that sharing a single struct_ops instance across multiple cgroups would be all that useful. If you map this to normal userspace programs, a given struct_ops instance is package of code and all the global data (maps). ie. it's not like running the same program multiple times against different targets. It's more akin to running a single program instance which can handle multiple targets. Maybe that's useful in some cases, but that program would have to explicitly distinguish the cgroups that it's attached to. I have a hard time imagining use cases where a single struct_ops has to service multiple disjoint cgroups in the hierarchy and it ends up stepping outside of the usual operation model of cgroups - commonality being expressed through the hierarchical structure. Thanks. -- tejun